Minimally invasive surgical techniques are aimed at reducing the amount of extraneous tissue that is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. As a consequence, the average length of a hospital stay for standard surgery may be shortened significantly using minimally invasive surgical techniques. Also, patient recovery times, patient discomfort, surgical side effects, and time away from work may also be reduced with minimally invasive surgery.
A common form of minimally invasive surgery is endoscopy, and a common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient's abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately one-half inch or less) incisions to provide entry ports for laparoscopic instruments.
Laparoscopic surgical instruments generally include an endoscope (e.g., laparoscope) for viewing the surgical field and tools for working at the surgical site. The working tools are typically similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by an extension tube (also known as, e.g., an instrument shaft or a main shaft). The end effector can include, for example, a clamp, grasper, scissor, stapler, cautery tool, linear cutter, or needle holder.
To perform surgical procedures, the surgeon passes working tools through cannula sleeves to an internal surgical site and manipulates them from outside the abdomen. The surgeon views the procedure from a monitor that displays an image of the surgical site taken from the endoscope. Similar endoscopic techniques are employed in, for example, arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy, and the like.
Minimally invasive telesurgical robotic systems are being developed to increase a surgeon's dexterity when working on an internal surgical site, as well as to allow a surgeon to operate on a patient from a remote location (outside the sterile field). In a telesurgery system, the surgeon is often provided with an image of the surgical site at a control console. While viewing a three dimensional image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master input or control devices of the control console. Each of the master input devices controls the motion of a servo-mechanically actuated/articulated surgical instrument. During the surgical procedure, the telesurgical system can provide mechanical actuation and control of a variety of surgical instruments or tools having end effectors that perform various functions for the surgeon, for example, holding or driving a needle, grasping a blood vessel, dissecting tissue, or the like, in response to manipulation of the master input devices.
In many existing minimally invasive telesurgical robotic systems, manipulation of the surgical instruments is provided by a surgical robot having a number of robotic arms. Each of the robotic arms has a number of robotic joints and a mounting fixture for the attachment of a surgical instrument. Integrated in with at least one of the mounting fixtures are a number of drive couplers (e.g., rotary drive couplers) that drivingly interface with corresponding input couplers of a surgical instrument. The surgical instrument includes mechanisms that drivingly couple the input couplers with an associated motion of the surgical instrument (e.g., main shaft rotation, end effector pitch, end effector yaw, end effector jaw clamping, deployment of staples, tissue cutting, etc.). In many existing minimally invasive telesurgical robotic systems, each of the drive couplers of the surgical robot are cable driven so as to, for example, provide for precise control over the movement of the output couplers as is possible in cable driven actuation systems. By precisely controlling the movement of the output couplers, precise control over the associated motions of the surgical instrument can be achieved.
A cable driven output coupler typically has a limited range of motion. Such a limited range of motion may not be detrimental where the output coupler is associated with a motion of the end effector that is not impacted by any other motion of the end effector. Such a limited range of motion may, however, be detrimental where the output coupler is associated with a motion of the end effector that is impacted by another motion of the end effector. For example, instrument shaft rotation may detrimentally couple with rotation of a drive shaft used to actuate an end effector mechanism (e.g., a clamping mechanism, a mechanism for the deployment of staples, a tissue cutting mechanism, etc.). Although compensating motions of the output couplers associated with the rotation of the instrument shaft and rotation of the drive shaft can be made, such compensating motions reduce the portion of the limited range of motion of the output couplers that can be used for their primary purpose.
Thus, there is believed to be a need for surgical assemblies and related methods for decoupling related motions of a surgical instrument, particularly decoupling instrument shaft roll and end effector actuation in a surgical instrument.
Manipulation and control of these effectors is also a particularly beneficial aspect of robotic surgical systems. For this reason, it is desirable to provide surgical tools that include mechanisms that provide three degrees of rotational movement of an end effector to mimic the natural action of a surgeon's wrist. Such mechanisms should be appropriately sized for use in a minimally invasive procedure and relatively simple in design to reduce possible points of failure. In addition, such mechanisms should provide an adequate range of motion to allow the end effector to be manipulated in a wide variety of positions.
Non-robotic linear clamping, cutting and stapling devices have been employed in many different surgical procedures. For example, such a device can be used to resect a cancerous or anomalous tissue from a gastro-intestinal tract. Many known surgical devices, including known linear clamping, cutting and stapling devices, often have opposing jaws that are used to manipulate patient tissue.
For known devices having opposing jaws, a significant amount of mechanical power must be delivered to the end effector to effectively, for example, clamp tissue, staple tissue, cut tissue, etc. In most cases, the main shaft of the instrument must react at least a portion of mechanical forces and/or torques delivered to the end effector, whether via compression of the main shaft to react a tensile force or via torsion of the main shaft to react a torque delivered via a drive shaft disposed within the main shaft. If the main shaft or the mechanism used to rotationally position the main shaft, is not sufficiently rigid, the main shaft may move unexpectedly in response to the reacted force or torque.
Thus, there is also believed to be a need for a surgical assembly that transmits high actuation torque to an end effector that does not experience unintended rotation of an independently rotatable main shaft used to support the end effector due to the transmitted actuation torque.